What is the importance of microtubules in cell division?
A.They provide a pathway for organelles to move into the newly formed cell.
B.They start the process of cytokinesis.
C.They reform the nucleus in the divided cell.
D.They organize and pull the chromosomes apart.
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The correct answer is D. Microtubules are critical structures in cell division as they are responsible for organizing and separating the chromosomes during the process of mitosis or meiosis.
To understand how microtubules are important in cell division, we can break down the process step by step:
1. Prophase: Microtubules form a structure known as the spindle apparatus, which consists of two centrosomes (microtubule organizing centers) and microtubules radiating from them. These microtubules attach to the chromosomes at specialized structures called kinetochores.
2. Prometaphase: The microtubules from the spindle apparatus attach to the kinetochores of the chromosomes. This attachment is crucial for proper alignment and segregation of the chromosomes during later stages.
3. Metaphase: The microtubules exert tension on the chromosomes, aligning them at the center of the cell on the metaphase plate. This ensures that each daughter cell receives the correct number of chromosomes during division.
4. Anaphase: The microtubules shorten and pull the sister chromatids apart by disassembling at the kinetochore end and losing tubulin subunits. This movement ensures that each daughter cell receives one copy of each chromosome.
5. Telophase: Microtubules continue to play a role in cytokinesis, the physical separation of the two daughter cells. They help to form the contractile ring, which pinches the cell membrane inward, leading to the formation of two separate cells.
Therefore, the correct answer is D: Microtubules organize and pull the chromosomes apart during cell division.